Responsa for Shabbat 14:2
אלא אכרמלית דאין כרמלית למעלה מי' ואקילו בה רבנן מקולי רה"י ומקולי רה"ר מקולי רה"י דאי איכא מקום ארבעה הוא דהויא כרמלית ואי לא מקום פטור בעלמא הוא מקולי רה"ר דעד י' טפחים הוא דהויא כרמלי' למעלה מי' טפחים לא הויא כרמלי':
if below ten, it is as though he throws it on to the ground.<span class="x" onmousemove="('comment',' And since it traverses four cubits, he is liable. — Why then need Samuel state it? ');"><sup>3</sup></span> Hence he must refer to a <i>karmelith</i>, [teaching] that there is no <i>karmelith</i> above ten. And [R. Dimi and R. Shesheth inform us that] the Rabbis treated it with the leniencies of both private and public ground. 'With the leniencies of private ground': that only if [it measures] four [handbreadths square] is it a <i>karmelith</i>, but if not it is simply a place of non-liability. 'With the leniencies of public ground': only up to ten is it a <i>karmelith</i>, but above ten it is not a <i>karmelith</i>.
Teshuvot Maharam
A. He should fasten a board beneath the seat (within not more than three tefahim below the latrine walls) so that the feces first fall on the board and then into the ditch. Should the board break on the Sabbath, he would still be permitted to use the latrine on that day.
SOURCES: Cr. 178, 179; Pr. 96; L. 349; Mord. Shabb. 376; Hag. Mord. Shabb. 461; Tashbetz 38; Hag. Maim., Shabbat 15, 4; Kol Bo 31 (p. 34a). Cf. Terumat Hadeshen 66.